JP2023012744A - Lining concrete heating method and heating device - Google Patents

Abstract

To efficiently heat lining concrete C to an appropriate temperature without using complicated control means.SOLUTION: A heating device which heats lining concrete C placed on an inner wall of a tunnel, includes: a metal formwork 10 for molding an inner peripheral surface of the lining concrete C; a PTC heater 1 in contact with an inner peripheral surface of the formwork 10; a heat insulation material 2 for keeping the back of the PTC heater 1 warm; and a pressing mechanism 4 for pressing the PTC heater 1 against the inner peripheral surface of the formwork 10 via the heat insulation material 2.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a method and apparatus for heating lining concrete placed on the inner wall of a tunnel.

In general, when lining the inner wall of a tunnel with concrete, an arch-shaped formwork provided on a center truck as described in Patent Document 1 is used, and from the tunnel entrance, for each section where the formwork is provided, Concrete lining is placed. The concrete is demolded after a predetermined period of time has elapsed after placement, but if the concrete strength at the time of demolding is low, cracks or the like may occur in the lining concrete.

Therefore, in Patent Document 1, using a plurality of heating means for heating the formwork and its control means, a plurality of heating areas set by dividing the lining concrete in the circumferential direction are sequentially set in a predetermined cycle. Methods and apparatus for switched heating have been proposed. By sequentially switching and heating in a predetermined cycle, it is possible to reduce variations in the temperature of the entire lining concrete and increase the strength of the concrete almost uniformly.

Japanese Patent No. 5421413 JP-A-10-220005

However, in the method and apparatus of Patent Document 1, the heating time and the order of switching in each heating area in one cycle are set, and the heating time is feedback-controlled based on the temperature of the lining concrete detected in real time. A complicated control means was required.

By the way, in Patent Document 2, concrete is placed in the foundation formwork of a residential building, the foundation formwork is covered with an electric heating curing sheet containing a PTC linear heater, and the heating of the electric heating curing sheet is controlled to produce concrete. A curing method for basic concrete is described in which the is cured at a predetermined temperature.

However, Patent Document 2 does not describe or suggest the use of this electric heating curing sheet for heating the lining concrete of a tunnel. Moreover, since this electric heating curing sheet incorporates a PTC linear heater between two sheet materials made of vinyl chloride resin, etc., air with low thermal conductivity is placed between the sheet material and the PTC linear heater. can intervene. In addition, since the electric heating curing sheet is simply placed over the basic formwork, air with low thermal conductivity may intervene between the electric heating curing sheet and the basic formwork. Therefore, the heat of the PTC linear heater is not efficiently transmitted to the base mold. Therefore, even if this electric heating curing sheet is used to heat the lining concrete of a tunnel, it cannot be heated efficiently.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to efficiently heat lining concrete to an appropriate temperature without using complicated control means.

[1] Heating method for lining concrete In the heating method for heating the lining concrete placed on the inner wall of the tunnel,
A method for heating lining concrete, comprising heating a metal form for molding the inner peripheral surface of the lining concrete with a PTC heater in contact with the inner peripheral surface of the form.

Here, it is preferable to insulate the back of the PTC heater with a heat insulating material.

The heat insulating material is preferably made of foamed polystyrene resin. This is because it is easy to process, has high heat retention, and is lightweight.

It is preferable to press the PTC heater against the inner peripheral surface of the mold via a heat insulating material. This pressure eliminates the presence of an air layer between the PTC heater and the inner peripheral surface of the formwork, allowing the heat from the PTC heater to be evenly transferred to the formwork, thereby stably maintaining the curing temperature of the concrete. be.

[2] Heating device for lining concrete
A heating apparatus for lining concrete, comprising: a metal mold for molding the inner peripheral surface of the lining concrete; and a PTC heater in contact with the inner peripheral surface of the mold.

Here, it is preferable to include a heat insulating material for keeping heat behind the PTC heater.

The heat insulating material is preferably made of foamed polystyrene resin. This is because it is easy to process, has high heat retention, and is lightweight.

It is preferable to include a pressing mechanism that presses the PTC heater against the inner peripheral surface of the mold via a heat insulating material. This pressure eliminates the presence of an air layer between the PTC heater and the inner peripheral surface of the formwork, allowing the heat from the PTC heater to be evenly transferred to the formwork, thereby stably maintaining the curing temperature of the concrete. be.

In addition, a plurality of reinforcing protrusions are protruding from the inner peripheral surface of the formwork, and a PTC heater and heat insulating material are arranged between the two reinforcing protrusions. It is preferable to include a pressing mechanism that presses the PTC heater against the inner peripheral surface of the formwork through.

This pressing mechanism includes a rigid member that is pushed by the screw and presses the back surface of the heat insulating material, the rigid member does not deform when the back surface of the heat insulating material is pressed, and the rigid member is separate from the heat insulating material. or an integrated one can be exemplified.

The heat insulating material is a plate-like body with grooves formed on the surface facing the inner peripheral surface of the formwork,
The PTC heater has a linear shape and is housed in a groove.

[Action]
A PTC heater is an electric heater using a PTC element having PTC (Positive Temperature Coefficient) characteristics. When the PTC element is energized, it is initially at a low temperature and has a small resistance value, so a large current flows and the element temperature rises sharply. Then, when the element temperature exceeds the Curie temperature, the resistance value increases, so the amount of current decreases, and as a result, the amount of heat generated decreases. Therefore, the PTC heater has a self-temperature control function that maintains a stable thermal equilibrium state at a constant temperature without increasing the temperature above a predetermined temperature. Therefore, no sensors or circuits are required for temperature control or overheating prevention.
Then, by heating the metal formwork with the PTC heater that is in contact with the inner peripheral surface of the formwork, the heat of the PTC heater is efficiently transmitted to the metal formwork, and the formwork is heated. The lining concrete can be heated via the above-described self-temperature control function, which eliminates the need to separately provide a complicated control means as in Patent Document 1.

According to the present invention, lining concrete can be efficiently heated to an appropriate temperature without using complicated control means.

FIG. 1 is a partially exploded perspective view showing a heating apparatus for lining concrete according to an embodiment. 2, (a) is a partial perspective view, (b) is a IIb-IIb cross-sectional view, and (c) is a IIc-IIc cross-sectional view of the same heating device. FIG. 3 is a sectional view of the same heating device. FIG. 4 is a bottom view of the heating device viewed from below.

1. PTC Heater The PTC heater is not particularly limited, but examples include a linear heater in which a plurality of PTC elements are arranged side by side in one direction, a planar heater in which a plurality of PTC elements are dispersedly arranged, and the like. A linear PTC heater is preferable because it is easy to arrange on the mold.
Examples of the PTC element include, but are not limited to, those made of barium titanate, silicon carbide, or the like.

2. Heat Insulation Material The heat insulation material is not particularly limited, but examples thereof include those made of foamed resin, foamed rubber, glass wool, rock wool, calcium silicate, perlite, etc. As mentioned above, those made of expanded polystyrene resin are preferred.
The heat insulating material is preferably formed into a plate-like shape (including a bar-like shape whose width is equal to or smaller than its height) because it is easy to install on the mold.

3. Pressing Mechanism Although the pressing mechanism is not particularly limited, the aforementioned pressing mechanism using a screw is preferable because of its simple structure. The rigid member mentioned above is not particularly limited, but may be plate-shaped, bar-shaped, or angular-shaped.
As the pressing mechanism, a pressing mechanism using a spring can be exemplified.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4. FIG. The structure, shape, number, etc. of each part in the embodiment are examples, and can be changed as appropriate without departing from the scope of the invention.

As shown in FIG. 3, shotcrete S is applied to the inner wall of the tunnel by a shotting method.
A floor rail (not shown) is laid on the floor of the tunnel, and a self-propelled center truck (not shown) is installed on the floor rail. .
A placement space is formed between the shotcrete S and the formwork 10, and the lining concrete C is placed in the placement space.

The lining concrete C is sequentially poured from the wellhead because the center truck moves sequentially from the wellhead and the ready-mixed concrete is filled in each placing space formed along with the movement. Therefore, the pit side of the casting space is closed by the end surface of the existing lining concrete C, and the face side is closed by the gable formwork (not shown).

The lining concrete C heating apparatus of this embodiment is for heating the lining concrete C placed on the inner wall of the tunnel. A metal (steel) mold 10 for molding the inner peripheral surface of the mold, a PTC heater 1 in contact with the inner peripheral surface of the mold 10, and a heat insulating material 2 for insulating the back of the PTC heater 1, It includes a pressing mechanism 4 that presses the PTC heater 1 against the inner peripheral surface of the mold 10 via the heat insulating material 2 .

The formwork 10 is constructed by connecting a predetermined plurality of arch-shaped formwork elements 11 having a length of, for example, 1000 to 2000 mm in the tunnel length direction.
The formwork element 11 has a partially cylindrical surface portion 12 forming a space for placing, and a pair of fan-shaped side portions 13 that extend toward the inside of the tunnel by bending from the wellhead side end and the face side end of the surface portion 12 . , and a plurality of reinforcing projections 14 projecting from the inner peripheral surface of the surface portion 12 . The reinforcing projections 14 are shaped steel extending in the direction of the tunnel length. The formwork element 11 is formed by connecting a plurality of divided pieces in the circumferential direction of the inner wall of the tunnel. In FIG. As indicated by , it includes up to the portion corresponding to the lateral portion of the inner wall.

As the PTC heater 1, for example, Sekisui Plastics Co., Ltd.'s product name "Tech heater" (T9 series) is used. This is made by connecting a plurality of barium titanate-based PTC elements between two conductive wires arranged in parallel and covering them with a resin coating. It is a flat linear heater with flexibility. Connectors are provided at both ends of the heater.

As the heat insulating material 2, for example, a plate-like body made of foamed polystyrene resin is used. It has, for example, a length of 700-1700 mm, a height of 100-150 mm and a width of 100-250 mm. With the PTC heater 1 accommodated in the groove 3, the PTC heater 1 and the heat insulating material 2 are disposed between the two reinforcing projections 14 so that their length directions are aligned with the hole length direction. The portion of the PTC heater 1 exposed from the opening of the mold 10 is in contact with the inner peripheral surface of the surface portion 12 of the mold 10 .

The pressing mechanism 4 has a male screw 6 screwed into a female screw 5 implanted in a reinforcing convex portion 14, and is pressed against the lower surface of the heat insulating material 2 across the two reinforcing convex portions 14 and pushed by the male screw 6. and a rigid member 7 that presses the back surface of the heat insulating material 2 . For the rigid member 7, for example, a rectangular plywood that does not deform when the back surface of the heat insulating material 2 is pushed is used, and the male screws 6 pass through the four corners of the plywood. The pressing force of the PTC heater 1 can be adjusted by tightening the male screw 6 . Due to this pressing, an air layer is no longer interposed between the PTC heater 1 and the inner peripheral surface of the formwork 10, the heat of the PTC heater 1 is evenly transferred to the formwork 10, and the curing temperature of the concrete is stably maintained. drool. As shown in FIGS. 3 and 4, one rigid member 7 may press one heat insulating material 2 or may press a plurality of heat insulating materials 2 .

A method for heating the lining concrete C using the heating device configured as described above will be described together with a placing method.
(1) On the ground, the PTC heater 1, the heat insulating material 2, and the pressing mechanism 4 are set on the mold 10 in advance as described above, and the PTC heater 1 is wired for energization.
(2) The mold 10 is supported by a center, and the PTC heater 1 in contact with the inner peripheral surface of the mold 10 is energized to heat the mold 10 to a predetermined temperature.
(3) In this heated state, the lining concrete C is cast in the casting space between the shoring concrete and the formwork 10 .
(4) The mold 10 is left in place for a predetermined period of time after placing, and the heating by the PTC heater 1 is continued until demolding.

According to the heating device and the heating method of the embodiment described in detail above, the following effects are obtained.
(A) By heating the metal mold 10 with the PTC heater 1 in contact with the inner peripheral surface of the mold 10, the heat of the PTC heater 1 is efficiently transmitted to the metal mold 10. , the lining concrete C can be heated through the heating of the formwork 10, and the self-temperature control function described above eliminates the need to separately provide a complicated control means as in Patent Document 1. Also, since the PTC heater 1 does not overheat, there is no waste in energy consumption.

(a) Since the back of the PTC heater 1 is kept warm by the heat insulating material 2, the heat of the PTC heater 1 does not escape to the back and is efficiently transmitted to the mold 10. - 特許庁
(c) Since the back of the PTC heater 1 is protected by the heat insulating material 2 and the rigid member 7, the PTC heater 1 is less likely to be damaged.

(d) Since the pressing mechanism 4 has a function of pressing the PTC heater 1 against the inner peripheral surface of the mold 10 , the heat of the PTC heater 1 is efficiently transferred to the mold 10 .
(e) Since the pressing mechanism 4 is attached to the reinforcing convex portion 14, there is no need to separately provide a member for attachment.

(f) By heating the lining concrete C from the time it is placed until it is removed from the mold, unevenness in the curing temperature is suppressed, the difference between the internal temperature and the surface temperature is reduced, and the strength of the concrete is increased when it is young. , cracks and surface peeling due to temperature stress and insufficient initial strength can be prevented.

The present invention is not limited to the above embodiments, and can be embodied with appropriate modifications within the scope of the invention.

REFERENCE SIGNS LIST 1 PTC heater 2 Heat insulating material 3 Groove 4 Pressing mechanism 5 Female screw 6 Male screw 7 Rigid member 10 Formwork 11 Formwork element 12 Surface part 13 Side part 14 Reinforcement convex part C Lining concrete S Shotcrete

[1] Heating method for lining concrete In the heating method for heating the lining concrete placed on the inner wall of the tunnel,
A metal form for molding the inner peripheral surface of the lining concrete is disposed between two reinforcing protrusions of a plurality of reinforcing protrusions projecting from the inner peripheral surface of the form. Heating is performed by the PTC heater that is in contact with the inner peripheral surface of the PTC heater, and the heat insulating material placed behind the PTC heater is kept warm. A method for heating lining concrete, characterized by pressing a PTC heater against the inner peripheral surface of the formwork through .

The reason why the PTC heater is pressed against the inner peripheral surface of the mold through the heat insulating material is that the air layer is not interposed between the PTC heater and the inner peripheral surface of the mold due to the pressing, and the heat of the PTC heater is transferred to the mold. This is because the heat is evenly transferred to the concrete and the curing temperature of the concrete is kept stable.

[2] Heating device for lining concrete
A metal form for molding the inner peripheral surface of the lining concrete, and a plurality of reinforcing protrusions protruding from the inner peripheral surface of the form. The PTC heater is in contact with the inner peripheral surface of the PTC heater , and the heat insulating material disposed between the PTC heater and the heat insulating material that heats the back of the PTC heater. A heating device for lining concrete, comprising: a pressing mechanism for pressing against an inner peripheral surface of a formwork .

The reason for including a pressing mechanism that presses the PTC heater against the inner peripheral surface of the formwork via a heat insulating material is that the pressure eliminates the presence of an air layer between the PTC heater and the inner peripheral surface of the formwork, thereby preventing the PTC heater from intervening. This is because the heat is evenly transferred to the mold and the curing temperature of the concrete is kept stable.

Claims (11)

In the heating method for heating the lining concrete (C) placed on the inner wall of the tunnel,
A metal formwork (10) for forming the inner peripheral surface of the lining concrete (C) is heated by a PTC heater (1) in contact with the inner peripheral surface of the formwork (10). A method for heating the lining concrete. 2. A method for heating lining concrete according to claim 1, wherein a heat insulating material (2) is provided behind the PTC heater (1). 3. The method for heating lining concrete according to claim 2, wherein the heat insulating material (2) is made of foamed polystyrene resin. A method for heating lining concrete according to claim 1 or 2, wherein the PTC heater (1) is pressed against the inner peripheral surface of the formwork (10) through a heat insulating material (2). In the heating device for heating the lining concrete (C) placed on the inner wall of the tunnel,
Constructed including a metal formwork (10) for molding the inner peripheral surface of the lining concrete (C) and a PTC heater (1) in contact with the inner peripheral surface of the formwork (10) A lining concrete heating device characterized by: A heating apparatus for lining concrete according to claim 5, comprising a heat insulating material (2) for keeping heat behind the PTC heater (1). 7. The apparatus for warming lining concrete according to claim 6, wherein the heat insulating material (2) is made of foamed polystyrene resin. A heating apparatus for lining concrete according to claim 6 or 7, comprising a pressing mechanism (4) for pressing the PTC heater (1) against the inner peripheral surface of the formwork (10) via a heat insulating material (2). A plurality of reinforcing projections (14) protrude from the inner peripheral surface of the formwork (10), and a PTC heater (1) and a heat insulating material (2) are arranged between the two reinforcing projections (14), It includes a pressing mechanism (4) that presses the PTC heater (1) against the inner peripheral surface of the mold (10) through the heat insulating material (2) by screwing the screw (6) into the reinforcing protrusion (14). The heating device for lining concrete according to claim 6 or 7. The pressing mechanism (4) includes a rigid member (7) that is pressed by a screw (6) to press the back surface of the heat insulating material (2), and when the rigid member (7) presses the back surface of the heat insulating material (2), 10. The device for warming lining concrete according to claim 9, wherein the rigid member (7) is not deformable and is separate from or integrated with the heat insulating material (2). The heat insulating material (2) is a plate-like body having grooves (3) formed on the surface facing the inner peripheral surface of the formwork (10),
5. The PTC heater (1) is linear and accommodated in the groove (3), and the portion exposed from the opening of the groove (3) is in contact with the inner peripheral surface of the mold (10). 11. The heating device for lining concrete according to any one of 10.

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